This invention relates to a helix structure of great length for use in forming helix belts. It also relates to a method and an apparatus for producing such helix structures, and to helix belts formed from such structures.
German patent application (OS) No. 3,039,873 discloses a procedure for introducing filler material into helix structures which are to be made into a helix belt. In this procedure during formation, the helix structures are wound about the filler material. This mode of operation is disadvantageous, however, since it causes the filler material to become crimped. A crimped filler may give rise to difficulties. Thus, for example, it creates a risk that the filler will be blown out from between the helix windings when the helix belt is cleaned by a high pressure air jet.
Winding of the helix structure about the filler also limits the volume and hardness of the filler. In particular, excessive hardness of the filler causes deformation of the helix when wound on a mandrel. This can result in the helix becoming non-uniform and, therefore, useless.
It is also possible to push or draw the filler material into a formed helix belt. However, this technique is very cumbersome. Moreover, where a belt is very wide, its permeability cannot be sufficiently reduced, particularly in the case of an excessively strong filler material, since there arises a high friction between the latter and the inner helix surface.
It is therefore an object of the present invention to provide a helix structure of great length from which helix belts of uniform permeability can be produced.
It is a further object of the present invention to provide a method and apparatus for producing the aforementioned helix structures.
It is yet a further object of the invention to provide helix belts formed from such helix structures.